{"id":"CVE-2026-54571","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-54571","summary":"ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores…","details":"ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request containing an exactly 256-byte multipart boundary wraps _boundaryPosition from 255 to zero, prevents the boundary parsing loop from terminating, consumes excessive CPU, and triggers a FreeRTOS watchdog reset on affected ESP32 or ESP8266 devices. This issue is fixed in version 3.11.1.","published":"2026-09-17T19:16:50.843","modified":"2026-09-17T19:16:50.843","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/ESP32Async/ESPAsyncWebServer/commit/b928de7cbd7debcd6266ece6a6c46f10a86d3a6f","label":"ESP32Async/ESPAsyncWebServer@b928de7"},"references":[{"type":"WEB","url":"https://github.com/ESP32Async/ESPAsyncWebServer/commit/b928de7cbd7debcd6266ece6a6c46f10a86d3a6f"},{"type":"WEB","url":"https://github.com/ESP32Async/ESPAsyncWebServer/pull/445"},{"type":"WEB","url":"https://github.com/ESP32Async/ESPAsyncWebServer/releases/tag/v3.11.1"},{"type":"WEB","url":"https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-4phx-fcj6-46r4"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-09-17T19:16:50.843"}}